(1) Field of the Invention
The present invention relates to a package of a carbonaceous filament strand.
(2) Description of the Prior Art
A carbonaceous filament strand is conventionally produced by preliminarily heating an organic polymer filament, such as polyacrylonitrile filament, cellulosic filament, or pitch filament, in an oxidizing atmosphere and then carbonizing or graphitizing it in a high temperature oven in an inert atmosphere. The carbonaceous filament strand thus obtained is wound on a bobbin in a square-end cheese package for easy unwinding.
Recently, a demand has arisen for larger packages of 1 kg or more, sometimes as much as 10 kg, in order to save labor in the winding process and cut down on packaging costs and transportation expenses. It is very difficult, however, to produce large packages of carbonaceous filament strand.
To obtain a square-end cheese package of conventional synthetic filament yarn, a spindle-drive winder is generally utilized. In such a winder, the yarn is wound on a bobbin fitted onto a spindle shaft through a traverse guide reciprocated along the spindle shaft within a constant travelling width. In this case, so-called "thread dwell" occurs on the shoulders of the resultant package, corresponding to the turning points of the traverse motion of the traverse guide. The "thread dwell" tends to cause yarn slip-over from the shoulder of the package after the winding operation or prevents smooth unwinding of the yarn from the resultant package. Further, in case of the carbonaceous filament strand package, the thread dwell causes a deterioration of the package qualities, particularly, of the strength of the strand located at the shoulder portion.
In one method of eliminating the "thread dwell", a pressure roll is provided in the winder parallel to the spindle shaft. The pressure roll maintains light contact with the package surface, the spindle shaft gradually moving away from the pressure roll as the package enlarges. Any "dwell" is therefore pressed by the pressure roll to flatten the package surface.
While this method is effective for winding conventional synthetic filament yarn, it is not that applicable to a carbonaceous filament strand. A carbonaceous filament strand has a higher Young's modulus, a lower elongation, and an extremely weak bending strength compared to conventional synthetic filament yarn such as polyester or polyamide. Accordingly, when the thread dwell is pressed by the pressure roll, though the package surface becomes flat, filaments in the strand of the dwell portion are damaged, causing degradation of strength and generation of fluff. It is therefore important to eliminate thread dwell in a carbonaceous filament strand package without damaging the filament quality.